The present invention comprises an optimal spark ignition system based on an optimally designed, versatile, ultra-high efficiency, high energy, high pulse rate, multi-pulse capacitive discharge (CD) electronic ignition system.
The purpose of the system, designated as Rapid Pulsed Multi-Pulse Ignition, or Rapid Pulsed Ignition (RPI) for short, is to provide an easily incorporated and retrofitable ignition which will allow internal combustion engines to operate under lean air-fuel ratio mixture conditions through rapid firing multiple pulse ignition for high engine efficiency and low exhaust emissions. For the case of Diesel engines (Direct Injection (DI) engines) the system provides effective ignition of the fuel for reduced ignition delay time and more controlled combustion by providing many ignition sites during the short fuel injection period.
Current ignition and combustion related equipment are either ineffective or impractical for allowing engines to operate at the 22:1 air-fuel ratio necessary to meet the presently contemplated moderately strict European emission standards. In the U.S. for example, where emission standards have been in force for many years, the rich mixture (14.6:1 air-fuel ratio) three-way catalyst system is exclusively used for gasoline engines.
The conventional Kettering (inductive) ignition system is totally ineffective in providing ignition of mixtures leaner than about 18:1. Electronic ignition and Capacitive Discharge (CD) ignition are no better as they use the same extremely inefficient ignition coil and provide minimal ignition energy (electrical currents) to the spark. Conventional multiple pulse ignition systems such as U.S. Pat. No. 3,898,971 are superior to these, but suffer from having a low pulse rate and a low converter power supply efficiency and provide only slightly better lean mixture ignition properties. The typical time between pulses in an ignition burst or train is one to two milliseconds, representing a low pulse rate and low pulse duty cycle. This pulse rate is too low to be useful at anything but low RPM, and of marginal use in Direct Injection (DI) engines where the typical fuel injection time is one to two milliseconds.
Other systems fail to address and answer the fundamental questions of providing successful ignition by tailoring the pulsing characteristics for optimal ignition ability and for providing a high efficiency converter power supply to drive the capacitive discharge ignition system.